GC-MS Accuracy

[RedLeader]

[mods, you can move this to the Pill Testing forum if you don't want it here. I am submitting it here, though, since the amount of brainpower here is so much higher.]

My question stems from an odd situation that came up recently when testing Molly. The sample passed a GC-MS test with 1 part MDMA, so 100%, but then weird things occured with a home testing kit. No reaction on what was assumed to be a fully-functioning Marquis kit, to be specific.

People talk a lot about fooling home kits, so I am curious about exactly how exhaustive GC-MS testing results are. Could such be fooled by designer drugs *very* structurally-similar to MDMA? I know that it tests for a wide variety of substances, but would it be possible for a sample of Subsance X to fool chemists into believing it was MDMA through GC-MS? Or is this totally insane to even ask?

I am not asking for names of distinct compounds that could test as MDMA through GC-MS, as that would probably not be a good idea to talk about. Just *if* it's possible.

Occum's Razor leads me to believe that the chemists' kit was old or something, because it seems quite rediculous for something that tested as MDMA on GC-MS to not test as MDMA on a marquis kit as well. Regardless, though, I am still curious about *if* GC-MS can be fooled or not.

Thanks,
-RL

 

[nuke]

GC/MS peaks are pretty specific, especially if you have a control. It's a lot more likely for the marquis reagent to have been improperly mixed or expired than it is for the GC/MS to have given wrong results (unless someone just didn't do the GC/MS testing in the first place). 1H-NMR should confirm it.

Do you have the mass spec and the chromatograph on hand?

 

[RedLeader]

I don't have those on hand. I will try to request them tomorrow, but I don't know if that will be granted (wasn't part of the original price). If I can get that info, I'll present it here. As well, will ask about the use of a control. My money is on an improperly mixed reagent. Just seems like a professional lab would know if their reagent was bad. Especially if they're regularly doing advanced drug-testing

Thanks for the quick response, nuke.

 

[mimac]

Was it a pill or powder form?

What means 1 part mdma? Does it mean it's the only active part and the rest is filler or does it mean it's 100% mdma i.e. 1mg of MDMA in 1mg of powder (which I mightly doubt! as it is almost impossibile).

It could also mean that the concentration (of MDMA in the pill/powder) is so low that the marquis didn't pick it up - i.e. you have trace amounts of mdma, whick the GCMS could pick up (sensitivity in the ug range if it's properly calibrated).

Did you test the same batch/material? Sometimes you can mix up unlabeled powders...

Do you have anything else to test the marquis on? Test it.

A bioassay should tell what's inside

love, m

 

[RedLeader]

Was it a pill or powder form?

Powder

What means 1 part mdma? Does it mean it's the only active part and the rest is filler or does it mean it's 100% mdma i.e. 1mg of MDMA in 1mg of powder (which I mightly doubt! as it is almost impossibile).

The former. Though again, I don't know how quantitative the lab would be concerning what GC/MS would pick up as "filler." IMO it's kind of a bad move on the part of the lab if they detect higher parts of filler agents and just don't report it becuase it's not a "drug" per se.

It could also mean that the concentration (of MDMA in the pill/powder) is so low that the marquis didn't pick it up - i.e. you have trace amounts of mdma, whick the GCMS could pick up (sensitivity in the ug range if it's properly calibrated).

Ya this is a worry of mine. A friend of mine has tested the sample with a (different) marquis reagent and it gave a positive result. So I am somewhat happy there. But still, I'd think a professional lab, as nuke said, would confirm a bad reagent was bad...

Did you test the same batch/material? Sometimes you can mix up unlabeled powders...

I didn't test it, but a friend did (who did get a reaction). There was no mixing up of powders, that I am sure of!

Ideally I'd love to see this reagent examined, but I'm guessing it's long gone. The lab does a lot of testing and these results were delayed a fait bit.

 

[vecktor]

be very careful with GCMS results showing a trace amount, most commercial labs do not run a blank before the sample so there is a significant chance traces will carry over between samples. Though in this case carryover does not appear to be an issue.

the fillers are not usually extracted by the sample preparation method and so are not seen by the gcms.

GCMS has other problems when it comes to quantitative analysis, I for one would not take GC-MS data showing 99% of one thing at face value.

 

[MurphyClox]

How possible is it that a compound with the same empirical formula but significantly different structure was contained? In this case, the mass signal would be identical (but not the fragmentation pattern), but plain chemical analysis like with Marquis' could fail...

- Murphy

 

[RedLeader]

^ Interesting. Sorry, I'm still pretty naive when it comes to chemistry. Exactly what kind of testing would be required to identify a distinct fragmentation pattern?

the fillers are not usually extracted by the sample preparation method and so are not seen by the gcms.

Hmm... Another thing I now know.

I'd think a commerical lab that was paid good money to test a sample would not only give proportions of "drugs" active to one-another, but would also be able to easily tell me the ratio of 1 unit of MDMA to X units of powder. Is this not that easy?

Thanks again guys for the replies!

 

[Black]

In this case, the mass signal would be identical (but not the fragmentation pattern)

and neither the retention time in the GC. so very unlikely.
at parties the local drug testing organisation first gives some information based on retention time and then follows up an hour later with more detailed MS data; and i don't think that the facility where the op had his sample tested doesn't use controls.

my guess is low mdma concentration or old reagent (both already mentioned here)...

 

[RedLeader]

It ended up being an old reagent. Sample was tested with (different) kits and everything indicated 1 part MDMA. After experiencing it, I'd have to put my finger on 70/30 MDMA to random fillers. I know my body much better than the average user, and I know that this was MDMA almost surely from reflection alone.

All-in-all, just be careful, folks, with trusting that popular labs wouldn't be so careless as to miss something like a bad reagent. Going on a week now since asking specifics to the lab about this, and without getting any response

This thread can be closed by the mods either or after any new feedback comes through.

 

[Fjones]

Also worth noting is that a testing of "MDMA 1" apparently does NOT mean that 1 gram of the powder contains 1 gram of MDMA, as the results and your experience seem to indicate that any amount of inactive filler may still be present.

But the good news is that the site recently regained funding, so people only have to pay $40 now for this work to be done, which seems to be about what it's worth, given the potential for sloppy work.